What Everett Couldn't Know

In an impressive feat of combining modal metaphysics with fundamental quantum mechanics, Wilson (2020) presents a new genuine realist metaphysics of modality: Quantum Modal Realism. One of the main motivations for Wilson’s project is to do better than existent realist metaphysics of modality with regards to epistemic challenge: we should be able to explain our knowledge of modality. In this paper, I will argue that there is a significant worry for the epistemology of Wilson’s modal metaphysics, one that parallels Rosen’s objection to Lewis genuine modal realism. That is, quantum modal realism fails to explain why our ordinary methods for gaining modal knowledge are reliable. I argue that this means that with regards to the epistemic challenge, Wilson’s modal metaphysics is, at best, as well off as Lewis’, but potentially worse.